Depth-First Forwarding (DFF) in Unreliable Networks

This document specifies the Depth-First Forwarding (DFF) protocol for IPv6 networks, a data-forwarding mechanism that can increase reliability of data delivery in networks with dynamic topology and/or lossy links. The protocol operates entirely on the forwarding plane but may interact with the routing plane. DFF forwards data packets using a mechanism similar to a "depth-first search" for the destination of a packet. The routing plane may be informed of failures to deliver a packet or loops. This document specifies the DFF mechanism both for IPv6 networks (as specified in RFC 2460) and for "mesh-under" Low-Power Wireless Personal Area Networks (LoWPANs), as specified in RFC 4944. The design of DFF assumes that the underlying link layer provides means to detect if a packet has been successfully delivered to the Next Hop or not. It is applicable for networks with little traffic and is used for unicast transmissions only.